Figure 1.

In situ confocal Ca²⁺ imaging in WT and RyR2^R4496C+/− hearts: normal Ca²⁺ transients under resting conditions. A–B, Autonomous, synchronized Ca²⁺ transients driven by sinus rhythm in (A) WT and (B) RyR2^R4496C+/− hearts. Spontaneous Ca²⁺ waves or Ca²⁺ sparks were rarely detected during steady state beating under resting conditions. Bottom panels are spatial averages of Ca²⁺ signals from corresponding images. C, Boxplots of Ca²⁺ transients (amplitude, time to peak, and T₅₀ relaxation), ◆ and error bars inside the box denotes mean±SE. N=5–7 hearts, n=54 or 82 frames of transients (most of frames include multiple myocytes) for WT and RyR2^R4496C+/−, respectively. Green bars indicate edges of myocytes in this and subsequent figures.